The present invention relates to a processing solution supplementing apparatus and method for supplementarily supplying processing solutions to processing solution vessels used for processing operations, such as developing, bleaching and fixing of a photographic photosensitive material which has been exposed to light reflected from or passed through an original or to light obtained from electrical signals through photoelectric conversion.
In general, when, in an automatic developing unit using silver halogenide photographic photosensitive materials, a processing solution such as a developing solution is supplementarily supplied into the processing vessel, the quantity of supplement thereof is calculated according to the size and amount of photographic photosensitive materials to be optically exposed. That is, the processing solution is supplementarily supplied according to the total processing area of the photosensitive materials so that the latter can be continuously processed in a desired manner.
Generally, images formed by exposing photographic photosensitive materials differ in density from one another, and the densities of the images depend on the exposure conditions. Even if the images are equal in size, they are generally different in the amount of exposure. Accordingly, photographic photosensitive materials different in the amount of exposure differ in developing rate. The developing rate is one of the factors which greatly affects the required amount of supplimentation of the developing solution. That is, as the developing rate is increased, the developing capacity is decreased quicker. Thus, for a high developing rate, it is necessary to supplementarily supply a large quantity of developing solution. Such a requirement occurs for instance in the case where a number of originals high in density are processed. On the other hand, when the developing rate is low, only a small quantity of developing solution need be supplementarily supplied into the developing vessel, as in the case of processing a number of originals low in density.
Hence, if supplementation of the processing solution is carried out according only to the area which is to be processed, then the processing solution may be excessively supplied. As a result, the photosensitive material is not processed under the designated processing conditions, and accordingly it may not be satisfactorily finished. Therefore, it is necessary for the operator to visually inspect the finish of the photographic photosensitive material every certain period of time, thereby to control the quantity of supplement of processing solution. Thus, the operation of the conventional developing apparatus is troublesome. Especially with a color copying machine of a silver salt photographic type installed in many offices for instance, it is rather difficult for the operator to manually correct the quantity of supplement of processing solution.
On the other hand, Japanese Patent Application No. 232593/88 has disclosed an apparatus in which the quantity of supply of processing solution is calculated according to various factors other than the processing area, thereby to maintain the processing solution in the processing vessel unchanged in characteristic. This is incorporated by reference to the co-pending U.S. patent application Ser. No. 07/381,401.
For supplementing the processing solution in the processing vessel, for instance a pump can be operated to supply the processing solution into the processing vessel, or the processing solution may be allowed to freely drip into the processing vessel. In the former method, the operation of the pump is controlled to supply a correct quantity of processing solution. In the latter method, the operation of a valve for allowing the processing solution to drip is controlled.
However, those methods are disadvantageous in that even if the operation of processing solution supplying device such as a pump and valve is controlled according to a calculated quantity of supplementation of processing solution, sometimes the processing solution may not be supplied correctly in the calculated quantity of supplement because of an error in the quantity of supply or erroneous operation of the processing solution supplying device. Also, sometimes the capacity of the processing solution supplying means may make it impossible to supplementarily supply a sufficient quantity of the processing solution. Accumulation of small errors in the quantity of supply can result in a large error, thus obstructing correct supplementation of the processing solution. Hence, the operation of the processing solution supplying device must be high in reliability.